﻿/*!
 *  版权所有(C) 2021 ToolGood(林知君)
 *  GPLv3 License - http://www.gnu.org/licenses/gpl-3.0.html  
 */
using System;
using System.Net;
using System.Text.RegularExpressions;
using Microsoft.AspNetCore.Http;

namespace ToolGood.WebCommon
{
    public static partial class ObjectExtension
    {
        /// <summary>
        /// 获取真ip
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static string GetRealIP(this HttpContext context)
        {
            try {
                var t = context.Request.Headers;
            } catch (Exception) {
                return "";
            }

            string result = context.Request.Headers["HTTP_X_FORWARDED_FOR"];
            //可能有代理 
            if (!string.IsNullOrWhiteSpace(result)) {
                //没有"." 肯定是非IP格式
                if (result.IndexOf(".") == -1) {
                    result = null;
                } else {
                    //有","，估计多个代理。取第一个不是内网的IP。
                    if (result.IndexOf(",") != -1) {
                        result = result.Replace(" ", string.Empty).Replace("\"", string.Empty);

                        string[] temparyip = result.Split(",;".ToCharArray());

                        if (temparyip != null && temparyip.Length > 0) {
                            for (int i = 0; i < temparyip.Length; i++) {
                                //找到不是内网的地址
                                if (IsIPAddress(temparyip[i]) && temparyip[i].Substring(0, 3) != "10." && temparyip[i].Substring(0, 7) != "192.168" && temparyip[i].Substring(0, 7) != "172.16.") {
                                    return temparyip[i];
                                }
                            }
                        }
                    }
                    //代理即是IP格式
                    else if (IsIPAddress(result)) {
                        return result;
                    }
                    //代理中的内容非IP
                    else {
                        result = null;
                    }
                }
            }

            if (string.IsNullOrWhiteSpace(result)) {
                result = context.Request.Headers["REMOTE_ADDR"];
            }

            if (string.IsNullOrWhiteSpace(result)) {
                result = context.Connection.RemoteIpAddress.ToString();
            }
            return result;
        }

        private static bool IsIPAddress(string str)
        {
            if (string.IsNullOrWhiteSpace(str) || str.Length < 7 || str.Length > 15)
                return false;

            string regformat = @"^(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})";
            Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);

            return regex.IsMatch(str);
        }

        /// <summary>
        /// 获取 UserAgent
        /// </summary>
        /// <returns></returns>
        public static string GetUserAgent(this HttpContext context)
        {
            return context.Request.Headers["User-Agent"].ToSafeString();
        }

        public static bool IsLocalhost(this HttpContext context)
        {
            var localIpAddress = context.Connection.LocalIpAddress;
            var remoteIpAddress = context.Connection.RemoteIpAddress;

            var isLocalhost =
                (remoteIpAddress != null
                    && remoteIpAddress.ToString() != "::1"
                    && remoteIpAddress.Equals(localIpAddress))
                || IPAddress.IsLoopback(remoteIpAddress);
            return isLocalhost;
        }
    }
}
